👤 A W Maclean

Testicular adult granulosa cell tumors (AGCTs) are rare and show several clinical, pathological, and molecular differences with their ovarian counterparts. FOXL2 p.Cys134Trp, the ubiquitous molecular driver of ovarian AGCTs, is infrequent (~ 7%) in testicular AGCTs. Recently, FGFR1 hotspot mutations were reported as a potentially "alternative molecular driver" in FOXL2-wild type (WT) ovarian AGCTs. A systematic assessment of FGFR1 status has not been performed in testicular AGCTs. Recently, our group analyzed a series of twenty testicular AGCTs using two NGS panels that lacked coverage of FGFR1. Among twelve cases analyzed successfully, none harbored pathogenic FOXL2 variants. In this study, we reassessed the tumors from our prior series with an NGS panel that covers FGFR1. Among the 14 tumors (70%) that were sequenced successfully, none harbored pathogenic FGFR1 variants. Considering the AGCTs assessed in this study and those previously reported in the literature, none of the 24 tumors analyzed to date have shown pathogenic FGFR1 variants. The present study reinforces the concept that testicular sex cord-stromal tumors classified as AGCTs are different from ovarian counterparts. Show less

Demyelination occurs with aging and is exacerbated in neurodegenerative diseases. During demyelination, microglia upregulate expression of APOE, the gene encoding for the brain's primary lipid transport protein apolipoprotein E (ApoE), which also mediates microglial engulfment and elimination of myelin debris. Compared to the E3 allele of APOE, the E2 allele decreases risk for Alzheimer's disease (AD), while the E4 allele increases AD risk and is associated with an increased severity and progression of multiple sclerosis. Previous work shows that mice expressing E2 exhibit improved microglial function and remyelination compared to mice expressing E4. However, whether microglial-derived APOE is responsible for driving these differences following demyelination, and if microglia-selective expression of E2 is sufficient to provide protection, is unknown. We sought to determine if microglia-specific replacement of the E4 allele with E2 can rescue myelin loss and promote remyelination, even in the presence of continued E4 expression by other central nervous system (CNS) cells. Using a novel APOE allelic "switch" model in which we can induce a replacement of E4 with E2 exclusively in microglia, we characterize the glial cell response and lipid profile of mice that underwent either lysophosphatidylcholine (LPC) or cuprizone (CPZ)-induced demyelination and subsequent remyelination. We found that although alterations to the brain lipid profile were subtle, microglial E2 replacement significantly improved remyelination, lessened microgliosis, and decreased astrocytic lipid droplet load following CPZ-remyelination. Our results indicate that microglia-specific E2 expression, in the presence of continued E4 expression, may provide protection against myelin loss via both cell-autonomous and non-autonomous immunometabolic mechanisms. Show less

Understudied orphan GPCRs lack identified natural ligands, yet understanding their function is critical for therapeutic development. GPRC5B is a brain-enriched, retinoic acid (RA)-induced orphan GPCR. While RA is used to treat severe acne, chronic exposure is associated with depression, likely due to its inhibition of adult hippocampal neurogenesis. Here, we tested whether GPRC5B plays a role in the molecular and cellular mechanisms underlying RA-induced depressive-like behaviors in mice by suppressing adult hippocampal neurogenesis. We found that Gprc5b knockout (KO) mice were resilient to RA-induced behavioral effects and that RA increased GPRC5B expression in the hippocampal neurogenic subgranular zone. This correlated with RA-mediated inhibition of adult hippocampal neurogenesis, an effect absent in Gprc5b KO mice, which also exhibited a larger pool of proliferative neuronal stem cells. Collectively, these findings suggest that GPRC5B mediates RA-induced anti-neurogenic effects and depressive-like behaviors. Show less

Liver X receptors (LXRs) are ligand-dependent transcription factors activated by cholesterol metabolites. These receptors induce a suite of target genes required for de novo synthesis of triglycerides and cholesterol transport in many tissues. Two different isoforms, LXRα and LXRβ, have been well characterized in liver, adipocytes, macrophages, and intestinal epithelium among others, but their contribution to cholesterol and fatty acid efflux in the lactating mammary epithelium is poorly understood. We hypothesize that LXR regulates lipogenesis during milk fat production in lactation. Global mRNA analysis of mouse mammary epithelial cells (MECs) revealed multiple LXR/RXR targets upregulated sharply early in lactation compared with midpregnancy. LXRα is the primary isoform, and its protein levels increase throughout lactation in MECs. The LXR agonist GW3965 markedly induced several genes involved in cholesterol transport and lipogenesis and enhanced cytoplasmic lipid droplet accumulation in the HC11 MEC cell line. Importantly, in vivo pharmacological activation of LXR increased the milk cholesterol percentage and induced sterol regulatory element-binding protein 1c (Srebp1c) and ATP-binding cassette transporter a7 (Abca7) expression in MECs. Cumulatively, our findings identify LXRα as an important regulator of cholesterol incorporation into the milk through key nodes of de novo lipogenesis, suggesting a potential therapeutic target in women with difficulty initiating lactation. Show less

The objective of the study was to examine the interaction of moderate and high dietary fat and ethanol with respect to formation of steatosis and regulation of the AMP-activated protein kinase (AMPK) pathway in a mouse model of chronic ethanol consumption. Male C57BL/6J mice were pair-fed a modified Lieber-DeCarli diet composed of either moderate fat [30% fat-derived calories (MF)] or high fat [45% fat-derived calories (HF)] combined with increasing concentrations of ethanol (2%-6%) for 6 weeks. Chronic ethanol consumption resulted in significant increases in plasma alanine aminotransferase in MF (1.84-fold) and HF mice (2.33-fold), yet liver triglycerides only increased significantly in the HF model (1.62-fold). Ethanol addition significantly increased plasma adiponectin under conditions of MF but not HF. In combination with MF, the addition of ethanol significantly decreased total and hepatic pThr(172)AMPKα and acetyl CoA Carboxylase (ACC). HF plus ethanol decreased pSer(108)AMPKβ, yet a marked 1.5-fold increase in pThr(172)AMPKα occurred. No change was evident in pSer(79)ACC under conditions of ethanol and HF ingestion. In both models, nuclear levels of sterol response element binding protein 1c and carbohydrate response element binding protein were decreased. Surprisingly, MF plus ethanol significantly elevated protein expression of medium-chain acyl-CoA dehydrogenase (MCAD), long-chain acyl-CoA dehydrogenase (LCAD) and very long chain acyl-CoA dehydrogenase but did not significantly affect mRNA expression of other proteins involved in β-oxidation and fatty acid synthesis. HF plus ethanol significantly reduced mRNA expression of both stearoyl CoA desaturase 1 and fatty acid elongase 5, but did not have an effect on MCAD or LCAD. These data suggest that, when co-ingested with ethanol, dietary fat differentially contributes to dysregulation of adiponectin-dependent activation of the AMPK pathway in the liver of mice. Show less

Major depressive disorder (MDD) is a common complex disorder with a partly genetic etiology. We conducted a genome-wide association study of the MDD2000+ sample (2431 cases, 3673 screened controls and >1 M imputed single-nucleotide polymorphisms (SNPs)). No SNPs achieved genome-wide significance either in the MDD2000+ study, or in meta-analysis with two other studies totaling 5763 cases and 6901 controls. These results imply that common variants of intermediate or large effect do not have main effects in the genetic architecture of MDD. Suggestive but notable results were (a) gene-based tests suggesting roles for adenylate cyclase 3 (ADCY3, 2p23.3) and galanin (GAL, 11q13.3); published functional evidence relates both of these to MDD and serotonergic signaling; (b) support for the bipolar disorder risk variant SNP rs1006737 in CACNA1C (P=0.020, odds ratio=1.10); and (c) lack of support for rs2251219, a SNP identified in a meta-analysis of affective disorder studies (P=0.51). We estimate that sample sizes 1.8- to 2.4-fold greater are needed for association studies of MDD compared with those for schizophrenia to detect variants that explain the same proportion of total variance in liability. Larger study cohorts characterized for genetic and environmental risk factors accumulated prospectively are likely to be needed to dissect more fully the etiology of MDD. Show less

Classical homocystinuria (HCU) is caused by mutations in cystathionine beta-synthase (CBS) which, if untreated, typically results in cognitive impairment, thromboembolic complications and connective tissue disturbances. Paraoxonase-1 (PON1) and apolipoprotein apoA-I are both synthesized in the liver and contribute to much of the cardioprotective effects of high density lipoprotein. Additionally, apoA-I exerts significant neuro-protective effects that act to preserve cognition. Previous work in a Cbs null mouse model that incurs significant liver injury, reported that HCU dramatically decreases PON1 expression. Conflicting reports exist in the literature concerning the relative influence of homocysteine and cysteine upon apoA-I expression. We investigated expression of PON1 and apoA-I in the presence and absence of homocysteine lowering therapy, in both the HO mouse model of HCU and human subjects with this disorder. We observed no significant change in plasma PON1 paraoxonase activity in either mice or humans with HCU indicating that this enzyme is unlikely to contribute to the cardiovascular sequelae of HCU. Plasma levels of apoA-I were unchanged in mice with mildly elevated homocysteine due to CBS deficiency but were significantly diminished in both mice and humans with HCU. Subsequent experiments revealed that HCU acts to dramatically decrease apoA-I levels in the brain. Cysteine supplementation in HO mice had no discernible effect on plasma levels of apoA-I while treatment to lower homocysteine normalized plasma levels of this lipoprotein in both HO mice and humans with HCU. Our results indicate that plasma apoA-I levels in HCU are inversely related to homocysteine and are consistent with a plausible role for decreased expression of apoA-I as a contributory factor for both cardiovascular disease and cognitive impairment in HCU. Show less